1. Field of the Invention
This invention relates to an improved electric arc furnace construction and to a liftable furnace roof from which the smoke hole hood is eliminated, and in which a side segment of the roof cooperates with a side segment of the furnace wall to provide a smoke chest and indirectly, a smoke hole. Another phase of the invention deals with a furnace roof which may be raised and swung-off the furnace as a unit, and which has a central crown portion which may be raised and swung for maintenance and repair independently of its outer or brim portion.
2. DESCRIPTION OF THE PRIOR ART
Heretofore, it has been customary to provide an electric arc furnace roof, not only with a central area for bypassing the electrodes, but also with a hood which defines a smoke hole portion and, in effect, further defines a smoke chest. Such a construction is advantageous from the standpoint of removing exhaust gases from the highest point of the furnance, but has disadvantageous features of materially increasing the height and complexity of the roof construction, and of maximizing initial cost and maintenance or repair expense. Also, such a hood has a tendency to increase the temperature to which the roof is subjected at the exhaust area and thus, to complicate the application of supporting and load carrying metal structure as well as the protective cooling thereof.
A roof hood, in addition to increasing the overall weight of the furnace roof, lends inflexibility to the construction from the standpoint of, for example, preventing an off-centered positioning of its central electrode area or crown. Operating experience has indicated that the hottest portion of an electric furnace is normally the portion adjacent the roof-manipulating metal tower. Flexibility in the construction of the roof is thus desirable in order to permit the central electrode hole carrying or crown portion thereof to, if desired, be offset backwardly from the tower.